A new user has asked a question about map making, specifically on how to figure out distances for a map they made.
While the question, in its current form, is off-topic for the site's format, it seems like there is useful information there if only it were phrased in a more specific, RPG-related way. Map making is part of the job of most DMs, after all.
How should this question be workshopped? What are the problems with it and how should those be addressed?
It's not off-topic. Asking for help with mapmaking is a perfectly valid question for the site. As SSD points out, we have a map-making tag, and it has some perfectly good questions in it. Note that it wasn't closed as off-topic, it was closed as unclear.
Which brings me neatly to the next point: It is unclear. The OP made this map themselves, and is asking "How big is it?" How should we know how big it is? It's not our map, and it's not a map of our imaginary world.
It's also opinion-based. The only way to answer it is to answer "How big do you think it should be?", which is pretty much directly a survey for opinions. Both of the answers provided have elected to answer with "Well, how big do you think it should be? It's exactly that big." They include some suggestions for how to make that decision, but ultimately it still boils down to the OP deciding for themselves.
As long as I'm going through close vote reasons, it's also pretty broad. Even ignoring the above problems, answers could easily justify anything from "That map is the map of a tiny archipelago in the middle of the ocean" to "That map is a world map for a planet of similar size to Earth" or even "That map is the map for a world that is both flat and square".
In order to improve it, one way to go about that would be to tailor the question to the answers it received. This sounds kinda backwards, but given that the OP accepted SSD's answer, clearly they found it useful. So a question like "How can I determine the overall scale of my map?" might be better, and allow for answers that suggest things like "pick a small distance, decide how long you want that to be, and scale up from there" (example borrowed from SSD's answer).
As posed, this question has no answer and it might not be able to get work-shopped into an answerable form. Critically, though, I do not think that this makes it off-topic. I think that is often, and definitely in this case, a category error. Knowing the reasons that a question cannot be answered can be useful both for the asker and the community as a whole. But, I stress, there must be strong and well-articulated reasons for "there is no answer" to be a good answer. "I can't think of an answer," doesn't cut it.
(In this case, the reason is that terrain maps are widely understood to have fractal properties, meaning that it is nearly impossible to say if those features are small islands, big islands, or continent-scale land masses just by inspection.)
In order to be answered, what has to happen is that the asker's underlying (and probably at the time unconscious) assumptions about the map need to be teased out. (Probably in chat.) The existing answer takes one tack-- the underlying assumption about travel times.
Another tack is run with the idea that the planet is earth-sized, and then confirm that the map is the maps of the whole planet. And then try not to think too hard about map projections, because clearly if the asker had been thinking about map projection styles they would have had a characteristic scale in mind.
A third (related) tack would be to ask questions about, say, cold zones in the north or south (i.e., are there polar effects that would break the fractal assumption at high ends.)
Without such information, the answer is, "There is no answer, here's why." With such information, the question might have a more direct answer or estimate.
